Symfony2：如何返回发送表单请求的页面

I have a link: mysite/productnumber_2.html. On this Site I have a formular in a twig template, the action of this form leads to .../createAssessment.

In my controller I do things like save in a DB.

My question is, how can I go back to the url mysite/productnumber_2.html?

My function in teh controller looks like this:

/**
 *
 * @Route(path = "/createassessment", name="create_assessment", methods = "POST")
 * @param Request $request The Request object
 * @return RedirectResponse
 */
public function createAssessmentAction(Request $request) {
$form = $this->createForm(new AssessmentType());
$form->handleRequest($request);

if ($form->isValid()) {

    $assessment = $form->getData();

    $em = $this->getDoctrine()->getManager();

    $em->persist($assessment);
    $em->flush();

    return $this->redirect( ## WHAT DO I HAVE TO PUT HERE?? ## );
}
}

You could redirect for request referer:

return $this->redirect($request->headers->get('referer'));

Or even better for defined route:

return $this->redirect($this->generateUrl('your_route'));

where your_route is path to you mysite/productnumber_2.html page.